[ScheduleOptimizer] Fix minor typo [NFC]

llvm-svn: 305709
diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 6b0848b..a7b174a 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -247,7 +247,7 @@
                                         unsigned OutDimsNum) {
   unsigned Dims = IsolateDomain.dim(isl::dim::set);
   assert(OutDimsNum <= Dims &&
-         "The isl_set IsolateDomain is used to describe the range of schedule "
+         "The isl::set IsolateDomain is used to describe the range of schedule "
          "dimensions values, which should be isolated. Consequently, the "
          "number of its dimensions should be greater than or equal to the "
          "number of the schedule dimensions.");